Alpha process

Triple-alpha process The nuclear process resulting in the fusion of three He nuclei or alpha particles to form 12C. 

Zhang, Z. et al., Inhibition of TNF-alpha processing and TACE-mediated ectodomain shedding by ethanol, JLeukoc. Biol., 67, 856, 2000. 

Alpha process C2H4, CO, CH3OH, H2CO Catalytic carbonylation of ethylene to Lucite (to become... 

Figure 3.2 In the triple alpha process, three helium nuclei collide to eventually produce carbon. This process occurs in extremely hot stars.

Because three a-particles combine to form 12C, this process is known as the triple-alpha process. Oxygen-16 is also produced during helium burning through the reaction 12C(a,y)160. 

The triple-alpha process is possible in the dense cores of massive stars. The process involves the essentially simultaneous fusion of three 42He2+ to form 126C6+ (Faure, 1998, 17-18). As the first step ... 

Triple-alpha process The formation of a carbon-12 nucleus in the interior of a massive star through the essentially simultaneous fusion of three helium nuclei. 

Chen, M., and Fernandez, H. L. (2004). Stimulation of beta-amyloid precursor protein alpha-processing by phorbol ester involves calcium and calpain activation. Biochem Biophys Res Commun 316, 332-340. 

Merlos-Suarez A, Femandez-Larrea J, Reddy P, Baselga J, Arribas J. Pro-tumor necrosis factor-alpha processing activity is tightly controlled by a component that does not affect notch processing. J Biol Chem 1998 273 24,955-24,962. 

Helium normally has two protons, two neutrons, and two electrons. An alpha particle is another name for the positively charged nucleus of the helium-4 atom. Alpha particles are emitted by some radioactive substances. But let me clarify why the triple-alpha process is so difficult and so wonderful. Triple-alpha process says Miss Muxdroozol. 

But there s some bad news. The speed of the two-step triple-alpha process to produce carbon depends on how much beryllium-8 resides in a star to be slammed into. And, we know that there is only one nucleus of beryllium-8 for every billion nuclei of helium. A very tiny amount According to astronomers ... 

This is what they thought at first. I m giving you a bit of history here. The reaction of beryllium-8 and helium-4 seemed too slow. There was one chance that the reaction speed could be boosted—if carbon-12 had a very special property an energy almost exactly equal to the combined energy of beryllium-8 and helium-4 at temperatures in a red giant. Chemists called this kind of facilitated nuclear reaction resonant. If by some miracle this were true, then the triple-alpha process could work. ... 

Okay, I ve showed you how a fortuitous two-step triple-alpha process can create carbon-12. But what happens if another helium-4 slams into the carbon-12 No answer, Mr. Plex Okay, I ll tell you. The carbon-12 is converted to oxygen-16. ... 

This book is dedicated to the triple alpha process and the number 7.6549 the reasons we are alive today, and smiling, on Earth. 

Primary nucleosynthesis Some astronomical evidence suggests that 13C nucleosynthesis has a primary component that is, a production rate in stars that does not rely on the prior presence of carbon in the interstellar gas from which the stars formed (see below). This is attested to by nitrogen also having a primary component (see 14N). This can occur in a red AGB star, which is creating new 12C by the triple-alpha process in a helium-burning shell beneath its H-containing envelope. Such stars undergo... 

Scorim Process or SP (Cinpres-Scorim), Rheomolding Process or RP (Thermold s), and the Press Alpha Process or PAP (Sumitomo Heavy Industries and Sankyo Chemical Engineering of Japan) processes are examples of this method. The SP multi-live feed molding process where two packing pistons oscillate 180° out of phase and eliminate weld lines, etc. The RP system provides 3-D orientation based on the concept of melt rheology as a function of vibration frequency and amplitude as well as temperature and pressure. The equipment utilizes piston/type melt accumulators set up adjacent to the melt stream of the plasticator. Piston oscillates back and forth. The PAP system uses compression pins that are... 

Miller AC, Schattenberg DG, Malkinson AM, et al. 1994. Decreased content of the il 1 alpha processing enzyme calpain in murine bone marrow-derived macrophages after treatment with the benzene metabolite hydroquinone. Toxicol Lett 74(2) 177-184. 

Methyl methacrylate (MMA) is an important commodity since it is polymerized to give poly methylmethacrylate (PMMA), a strong, durable and transparent polymer sold under the trade-names Perspex and Plexiglas. Since the conventional routes to MMA involve either the reaction of acetone with HCN to give the cyanohydrin (which has environmental problems), or the oxidation of isobutene, alternative carbonylation routes to MMA are being developed. One of these is the Lucite Alpha process which is claimed to decrease production costs by ca. 40%. This first synthesizes methyl propionate by a methoxycarbonylation of ethylene (Equation 23), using a palladium catalyst with very high (99.8%) selectivity. In the second step, MMA is formed in 95% selectivity by the reaction of methyl propionate with formaldehyde (Equation 24). 

Redford EJ, Smith KJ, Gregson NA, Davies M, Hughes P, Gearing AJ, Miller K, Hughes RA (1997b) A combined inhibitor of matrix metalloproteinase activity and tumour necrosis factor-alpha processing attenuates experimental autoimmune neuritis. Brain 120 1895-1905. 

Figure 39. Relaxation rate of the alpha process versus inverse temperature for different thin PS films, as indicated. Inset. Dielectric loss (normalized) versus temperature at 31 kHz skHz showing the alpha relaxation of the same samples.

H.Oberhummer, A. Csoto and H. Schlattl. Fine tuning the basic forces of nature through the triple alpha process in red giant stars. Science, 289, 88 (2000). 

Fig. 11. Triple alpha process of 12C synthesis. In the first step a small amount of sBe nuclei builds up in equilibrium with its decay products (forward and backward reactions involve alpha particles). The second step involves a capture of another alpha particle by the unstable sBe nucleus which proceeds via an s-wave resonance state in the product nucleus 12 C located close to the Gamow energy window for temperatures indicated schematically by the three-way arrows on the right...

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